Creating a Peanut Butter Cup Chocolate Roll Cake can be straightforward if you follow these steps closely:

1. Preheat the Oven: Preheat your oven to 350°F (175°C). Line a 15×10-inch jelly roll pan with parchment paper and grease lightly.

2. Make Chocolate Cake Batter:
– In a medium bowl, combine flour, granulated sugar, cocoa powder, baking powder, baking soda, and salt.
– In another bowl, whisk together the eggs, oil, and vanilla extract.
– Gradually add the wet ingredients to the dry ingredients, stirring until combined.
– Carefully incorporate the boiling water (the batter will be thin, which is normal).

3. Bake the Cake:
– Pour the batter into the prepared pan, spreading it evenly.
– Bake for 15-20 minutes, or until a toothpick inserted comes out clean.

4. Cool the Cake:
– Once baked, immediately remove it from the oven and let it cool in the pan for 5 minutes.
– Carefully, invert the cake onto a clean kitchen towel dusted with powdered sugar.

5. Roll the Cake:
– Starting at one end, gently roll the cake with the towel inside. Allow it to cool completely in its rolled form, which helps retain its shape.

6. Prepare the Peanut Butter Filling:
– In a bowl, combine the creamy peanut butter, powdered sugar, softened butter, and vanilla extract.
– Mix until smooth and creamy, adding milk as needed for a spreadable consistency.

7. Fill the Cake:
– Once the cake has cooled completely, carefully unroll it.
– Spread the peanut butter filling evenly over the cake, leaving a small border at the edges.

8. Re-Roll the Cake:
– Gently re-roll the cake without the towel, starting from one end.
– Wrap it tightly in plastic wrap and chill in the refrigerator for at least 30 minutes.

9. Make the Chocolate Ganache:
– In a small saucepan, heat the heavy cream over medium heat until it begins to simmer.
– Remove from heat and pour over the chocolate chips in a bowl. Let it sit for about 5 minutes, then stir until smooth.

10. Assemble the Cake:
– Once chilled, unwrap the cake and place it on a serving plate.
– Drizzle or spread the chocolate ganache over the top, allowing it to drip down the sides.

11. Slice and Serve:
– Use a sharp knife to slice the cake into pieces, showcasing the beautiful layers.